〔Abstract〕 Objective To observe the therapeutic effect of low molecular weight heparin calcium (LMWH) graded perinatal treatment on postpartum lower deep venous thrombosis (LDVT). MethodsThe data of pregnant women who had been registered and delivered in Sanming First Hospital from January 2020 to January 2022 were retrospectively selected. According to the prevention program of deep vein thrombosis, 884 pregnant women with routine program were selected as the control group, and 884 pregnant women with perinatal grading treatment were selected as the observation group. The changes of blood coagulation function indexes and lower limb venous blood flow velocity before and after delivery were compared between the two groups. The incidence of postpartum LDVT and the incidence of adverse reactions of antithrombotic therapy in the two groups were counted.Results After delivery, the prothrombin time (PT) and activated partial thromboplastin time (APTT) of the two groups were shorter than those before delivery, D-dimer (D-D) and platelet count (PLT) were higher than those before delivery, and the PT and APTT of the observation group were longer than those of the control group, and the D-D and PLT were lower than those of the control group, the differences were statistically significant (P < 0.05). The venous blood flow velocity of postpartum women in the two groups was faster than that before delivery, and the venous blood flow velocity of the observation group was faster than that of the control group, and the difference was statistically significant (P < 0.05). The LDVT and the incidence of adverse reactions in the observation group were lower than those in the control group, and the differences were statistically significant (P < 0.05). Conclusion LMWH can reduce the incidence of postpartum LDVT, and the treatment plan is safe and feasible.